Posted
by
timothy
on Friday June 10, 2011 @11:16AM
from the breathless-pursuit-works-best-if-anaerobic dept.

Velcroman1 writes "The quest for the elusive Higgs boson seemed over in April, when an unexpected result from an atom smasher seemed to herald the discovery of the famous particle — the last unproven piece of the physics puzzle and one of the great mysteries scientists face today.
Scientists with the Tevatron particle accelerator at Chicago's Fermilab facility just released the results of a months-long effort by the lab's brightest minds to confirm the finding. What did they find? Nothing. 'We do not see the signal,' said Dmitri Denisov, staff scientist at Fermilab. 'If it existed, we would see it. But when we look at our data, we basically see nothing.'"

The elegant standard model of particle physics only works because the particles don't have intrinsic mass (they get their mass from coupling to the higgs field). This allows a symmetry between the three "families" of particles (electron/muon/tau, neutrino/mu neutrino/tau neutrino, up/strange/top, down/charm/bottom etc.)

So if there is no Higgs boson then we're certainly missing something. I'm not sure if it's possible for the Higgs field to exist and not carry particles; certainly you'd normally expect for particles to be able to form in a field. If there's no Higgs field then either some other mechanism gives particles mass (and I'm not aware of any real proposals) or the standard model is wrong (which it probably is wrong, but we're short on replacements). If the standard model collapses, that puts us back to having 20+ different "fundamental" particles, all discovered through experiment, with no real idea of how they're related or how many more are out there.

First, to be clear: the Fermilab people haven't shown that the Higgs boson doesn't exist. They just didn't find it.

If the LHC doesn't find it, then we can start saying it doesn't exist. That would pretty much invalidate the standard model [stackexchange.com] of particle physics, which is the currently best-accepted theory we have (because it gets most things right). If the standard model is wrong, it opens the door for other physical theories [stackexchange.com] to be considered. Right now we're not taking those other theories so seriously because they all get one thing or another wrong, but if the standard model is also wrong about the Higgs, then there's no particular reason to favor it over other theories that also get one or two things wrong.

Some aspects of current science always need to be re-visited, and science in general isn't touchy about doing so.

There may not be a need for Higgs Boson as you suggest, but the current theories suggest that there is - which is why its being looked for. No one has yet come up with a credible alternative that doesn't first throw out the entire current model, and quite honestly its currently cheaper to spend the money looking for the Higgs Boson than it is recreating the entire current model from scratch and coming up with evidence to support the change.

But the chance that the Higgs Boson might not exist is not a reason not to look for it - because looking for it will either prove it does exist, or that it doesn't exist where we thought it did. Both outcomes are beneficial, and just because we didn't find it doesnt mean the money was wasted - the fact that it wasn't where we thought it was is great science in itself, because it brings new data to the table.

Plus of course the chance that other discoveries may be made during the hunt for the Higgs Boson.

Sorry, the summary and title is just plain incorrect. This announcement has nothing to do with the Higgs.

A few months ago, CDF claimed that they detected a new particle which could not be the higgs, but was speculated to be a new particle. As explained here [science20.com], it wasn't possible for the new particle to be the Higgs.

Today DZERO announced that they did not see any signal where CDF claimed to see one. So one of the two projects has an error in their analysis.

Currently, things weigh more than they should. The mass of a particle is a function of the kinetic energy of the particle and it's component parts, if any. If we run the numbers, we get good masses for some particles, not good masses for others. A proposed solution to this problem is the Higgs field, a nonzero field that permeates space. Anything coupling with this field gains additional mass through interaction with the field.

Picture a person at a party. Normally, they are free to move through the party fairly easily. Now make that person famous. Admirers flock around, and the celebrity has trouble moving. Nonfamous people are particles that do not couple with the HIggs field. Celebrities are particles that do couple with the field, surrounded by a paparazzi of virtual Higgs particles.

Nice theory. It fills a gap in the standard model and now the math all works. So now we have to find the particle. You need the mass of a particle to find it in an accelerator. Roughly (very roughly), you need to create collisions where the sum energy of the little explosion is about that of the particle in question, then watch a statistically large number of those to see if something matching your particle appears. If it does, it's off to Stockholm for dinner with the king. If not, it's back to the drawing boards.

The problem is, the theory doesn't predict the mass of the particle. It doesn't even say if it is one particle, a family of similar particles or a family of different particles. So there's a wide spread of masses to examine. And all the masses are really high, far higher than any other existing accelerator could reach. So we have the new CERN experiment, slowly scanning the possible masses, looking for the particle.

If we don't find that particle, then we're back to square one, why are some particles heavier than predicted? For decades, we've assumed it was some sort of variant of the Higgs boson. But if that's not the case, it's back to the blackboard for more theories.

In general, this is a problem for particle physics. Finding or not finding the particle will affect chemistry, biology and general astronomy not at all. It might or might not have an affect on cosmology, but that's hard to say without a particle to talk about. More interesting for cosmology is that while searching for the Higgs, the experiment might come across more esoteric things, such as evidence for supersymmetry. Evidence for supersymmetry would automatically generate the prime number one candidate for dark matter. And nailing down the properties of dark matter would give us another probe of the Big Bang.

Falsifiability [wikipedia.org] is when you describe an experiment that would show your theory to be false. Falsifiability is a requirement of a valid hypothesis. Gravity would be falsified by showing that objects with mass didn't accelerate towards each other - if you could show that, you disprove gravity. Evolution is falsified by watching a species spring from nothing. Creationism can't be falsified because "it's all God" - anything that happens that you didn't expect, God could've done - which is why creationism isn't science.

It's not about fabrications or hoaxes. The GP's question (I hope) is whether somebody could construct an experiment that shows that the boson *doesn't* exist, at least not as we understand it.

Suppose you have car and emperically you figure out how to drift it into many different turns. In certain configurations, you notice a certain amount of differential side-slip and you collect data. You make a theory about drifting based on various combinations of tires (particles), and road surface types (fields). One thing that you notice is that you don't really know why there's certain side-slip angles with different treads, so you propose a theory that the coupling between the tires and the road surface is different between these situations and that affects the skid dynamics (apparent mass), that you experience. Okay now you have this great theory and a bunch of empirical data of skid dyanmics that works for you by assigning magic number (masses) to various combination tires and surface types.

But you wonder if you can find a way to predict the dynamics and you come up with this idea that this coupling is a fundamental relationship of the coupling between tires and road surfaces (kinda like friction). Your theory is that there is some interaction between the tire and road which is like "friction" caused by the tread design and tire deformation amount. So you devise an experiment to see if you can find the thing causing this "friction".

The higgs field is analgous "friction" and the search for the higgs-boson is analagous to the search for the source of friction. If you think of friction being caused by atomic forces, there is some range of forces that can cause the macroscopic changes in skid dynamics that you see empirically. Likewize with Higgs, the higgs-boson need to be found in a certain range of collision energy if it is consistant with the standard model to match the empirical data of obverved mass and coupling constants up to Planck scale energies (where gravity is more quantized and mass probably has different physics).

If we find the thing that causes atomic forces that is consistant with our theory of "friction" (with say the tread design, or say the tire deformation amount), then probably something else explains the skid dynamics that isn't "friction", but something else. So we have to determine by experiment what the skid dynamics are for each tire and road combination. Likewize, with w/o Higgs we are struggling to have a theory of mass, but that doesn't mean mass (and the resultant dynamical behaviour) doesn't exist, just we don't know why it exists and can't predict it from known theories.